The ministry spokesman, however, denied a report that Japan and the United States plan to hold a joint missile defense exercise off the Japanese coast in January.

Japan will conduct the launch test from the Aegis-radar-equipped destroyer Kongo at an unspecified U.S. location in the Pacific Ocean around December, he said. The mass-circulation Yomiuri newspaper said the test would be conducted off Hawaii.

The destroyer, currently undergoing remodeling to be equipped with the SM-3 missile, will be ready soon, he added.

The official spoke on condition of anonymity under ministry protocol.

Japan last year participated in a U.S. navy missile launch test off Hawaii but it only involved tracking of targets fired by the U.S.

Tokyo and Washington have been jointly developing an advanced missile defense system. Japan deployed its first advanced U.S.-developed Patriot missiles this year, and plans to introduce the SM-3 intercepters on its destroyers over the next few years, including one later this year.

The ministry spokesman dismissed a report in the Yomiuri which said that in January Japan would hold a joint missile defense exercise with the United States, their first with both sides using SM-3 equipped Aegis destroyers. The report, quoting unidentified government officials, said the exercise would likely be conducted in the Sea of Japan, uses a scenario of a North Korean missile attack.

The report claimed that during the exercise, the Japanese and U.S. navies would deploy the same Aegis-loaded destroyers to help develop skills for joint operations.

"We don't have any joint exercise plans with the U.S.," the ministry spokesman said.

Japan has a mutual security pact with the United States guaranteeing that Washington would come to Tokyo's defense if it came under attack. Some 50,000 U.S. troops are deployed throughout Japan. Japan's own military is strictly limited by the constitution, which bans the use of force to settle international disputes.

The pacifist constitution strictly limits the Japanese military's use of force to self-defense and the missile defense system that would held defend the U.S. military is highly controversial.

Members of a government panel appointed by Japanese Prime Minister Shinzo Abe last week largely agreed that Japan should be able to shoot down a ballistic missile targeting the United States by stretching the interpretation of the bounds of its post-World War II pacifist constitution.